Four K-9 teams from the Maricopa County Sheriff's Office search and rescue assisted in the ground search, which consisted of an area from about the McClintock Drive bridge to almost Dobson Road. Pooley said they also searched the north side of the lake, but did not find any evidence.

Police said they remain focused on interviewing friends and fraternity brothers who were at the event that night. Detectives are trying to verify stories and review surveillance video at surrounding businesses, according to Pooley.

DNA on the shoe that was found by Culolias' mother is still being processed. Police hope to have it back by next week to confirm whether or not it belongs to him.

Investigators worry there may be people who may have seen Culolias leave Cadillac Ranch but haven't yet come forward. They are urging potential witnesses to leave tips anonymously through the Tempe Police Department's website, www.tempe.gov. Anyone with information can also call 480-350-8311.